Physicians evaluating erectile dysfunction typically order blood tests to measure testosterone levels. Supposedly, a low level of this male hormone indicates a low sex drive. But recent research suggests that testosterone level is not a good predictor of sex drive.
Researchers at Bassett Healthcare in Cooperstown, New York, examined the records of 108 men (average age 59) who had gone to an erectile dysfunction clinic. The men completed a questionnaire, called the "Sexual Function Inventory," and had a blood test that measured total testosterone and "free" testosterone (which is not bound to other substances) levels.
Half of the men had low sex drive, 35 percent had medium sex drive, and 14 percent had high sex drive. There were no group differences, however, in the men's testosterone levels. Total testosterone was almost identical in each of the three groups. Of the 49 men with testosterone levels below normal, 29 had low sex drive, 15 medium, and five had a high sex drive.
The researchers noted that among men with erectile dysfunction, only about 6.6 percent have low testosterone levels. Although scientists do not know what role testosterone plays in either sex drive or erectile dysfunction, U.S. Medicare guidelines recommend measurement of testosterone in men with erectile dysfunction if they report a loss of sex drive. And, it is common practice for doctors to routinely order these tests when evaluating men with erectile dysfunction.
The average cost of measuring total testosterone in the blood is $52 and $58 for measuring free testosterone. The researchers estimate that if testosterone tests are ordered for every man who seeks medical treatment for erectile dysfunction, the total cost would be about $419 million.
Since testosterone doesn't seem to predict sex drive and the researchers also found that total and free testosterone levels are closely related, there doesn't seem to be any reason to routinely order even one of these tests, not to mention both.
The researchers suggest that more research is needed to determine what role testosterone may play in sex drive and erectile dysfunction, but until more is known, it is a waste of money to order these tests. This study was published in the September 1999 issue of "The Journal of Urology."